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Global field

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in the nineteenth century. The more strict analogy expressed by the 'global field' idea, in which a Riemann surface's aspect as algebraic curve is mapped to curves defined over a finite field, was built up during the 1930s, culminating in the
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Algebraic number theory. Proceedings of an instructional conference organized by the London Mathematical Society (a NATO Advanced Study Institute) with the support of the International Mathematical Union
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It is usually easier to work in the function field case and then try to develop parallel techniques on the number field side. The development of
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There are a number of formal similarities between the two kinds of fields. A field of either type has the property that all of its
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consists of such local data that agree on the intersections of open affines. This technically defines the rational functions on
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is the set of all rational functions on that variety. On an irreducible algebraic curve (i.e. a one-dimensional variety
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also made use of techniques that reduced the number field case to the function field case.
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of the affine coordinate ring of any open affine subset, since all such subsets are dense.
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by multiplying the local components of an idĂšle class. One of the statements of the
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The analogy between the two kinds of fields has been a strong motivating force in
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is a dramatic example. The analogy was also influential in the development of
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The function field of an irreducible algebraic curve over a finite field
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over a global field are equivalent if and only if they are equivalent
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in 1940. The terminology may be due to Weil, who wrote his
918:(1946), "A note on axiomatic characterization of fields", 535:. It can be described in terms of cohomology as follows: 800: 788: 836: 313:). Every field of either type can be realized as the 581: 519:
Artin's reciprocity law implies a description of the
342: 141: 99: 57: 824: 812: 410:. The idea of an analogy between number fields and 686: 384: 273:is defined as the ratio of two polynomials in the 172:An axiomatic characterization of these fields via 160: 123: 65: 766:is that this results in a canonical isomorphism. 1114: 425:Riemann hypothesis for curves over finite fields 325:is of finite index. In each case, one has the 1077:, London: Academic Press, pp. 128–161, 910: 871: 806: 794: 435:(1967) in part to work out the parallelism. 1065:(1967), "VI. Local class field theory", in 297:Analogies between the two classes of fields 135:in one variable over the finite field with 474: 1098:, Springer Science & Business Media, 950:, "Global fields", in J.W.S. Cassels and 931: 894: 281:, and that a rational function on all of 102: 59: 980: 854: 842: 782: 508: 1115: 194:Function field of an algebraic variety 93:, equivalently, a finite extension of 1088: 1061: 1022: 830: 818: 183: 385:{\displaystyle \prod _{v}|x|_{v}=1,} 124:{\displaystyle \mathbb {F} _{q}(T)} 13: 572:describes a canonical isomorphism 14: 1144: 962:, 1973. Chap.II, pp. 45–84. 180:and George Whaples in the 1940s. 1036:, New York, Heidelberg, Berlin: 965:J.W.S. Cassels, "Local fields", 36:. There are two kinds of global 933:10.1090/S0002-9904-1946-08549-3 896:10.1090/S0002-9904-1945-08383-9 758:can be assembled into a single 32:) that are characterized using 668: 665: 647: 363: 354: 118: 112: 1: 864: 501:, i.e. equivalent over every 769: 533:Hasse local–global principle 66:{\displaystyle \mathbb {Q} } 7: 857:, p. 300, Theorem 6.3. 489:is a fundamental result in 469: 10: 1149: 967:Cambridge University Press 512: 478: 210:An algebraic number field 187: 237:is a field that contains 206:An algebraic number field 202:is one of the following: 807:Artin & Whaples 1946 795:Artin & Whaples 1945 442:and its exploitation by 321:in which every non-zero 1128:Algebraic number theory 986:Algebraic Number Theory 956:Algebraic number theory 487:Hasse–Minkowski theorem 481:Hasse–Minkowski theorem 475:Hasse–Minkowski theorem 408:algebraic number theory 261:A function field of an 214:is a finite (and hence 161:{\displaystyle q=p^{n}} 24:is one of two types of 920:Bull. Amer. Math. Soc. 882:Bull. Amer. Math. Soc. 785:, p. 134, Sec. 5. 688: 386: 329:for non-zero elements 307:locally compact fields 275:affine coordinate ring 190:Algebraic number field 162: 125: 67: 45:Algebraic number field 1034:Greenberg, Marvin Jay 764:Artin reciprocity law 750:for different places 724:of global fields and 703:local reciprocity map 689: 570:local reciprocity law 531:that is based on the 515:Artin reciprocity law 509:Artin reciprocity law 499:locally at all places 493:that states that two 387: 245:when considered as a 163: 126: 76:Global function field 68: 579: 446:in his proof of the 340: 139: 97: 55: 1123:Field (mathematics) 707:norm residue symbol 664: 609: 458:. The proof of the 433:Basic Number Theory 1090:Serre, Jean-Pierre 1063:Serre, Jean-Pierre 1024:Serre, Jean-Pierre 699:local Artin symbol 684: 650: 595: 564:with Galois group 527:of a global field 448:Mordell conjecture 382: 352: 315:field of fractions 291:field of fractions 184:Formal definitions 158: 133:rational functions 121: 63: 28:(the other one is 1105:978-1-4757-5673-9 999:978-3-540-65399-8 760:global symbol map 735:idĂšle class group 678: 464:Langlands program 460:fundamental lemma 420:Heinrich M. Weber 343: 263:algebraic variety 1140: 1133:Algebraic curves 1108: 1092:(29 June 2013), 1085: 1058: 1019: 982:Neukirch, JĂŒrgen 944: 935: 907: 898: 858: 852: 846: 840: 834: 828: 822: 816: 810: 804: 798: 792: 786: 780: 722:Galois extension 693: 691: 690: 685: 680: 679: 676: 663: 658: 646: 645: 644: 643: 634: 629: 628: 614: 608: 603: 591: 590: 558:Galois extension 523:of the absolute 416:Richard Dedekind 412:Riemann surfaces 399:varies over all 391: 389: 388: 383: 372: 371: 366: 357: 351: 228:rational numbers 174:valuation theory 167: 165: 164: 159: 157: 156: 130: 128: 127: 122: 111: 110: 105: 72: 70: 69: 64: 62: 49:finite extension 1148: 1147: 1143: 1142: 1141: 1139: 1138: 1137: 1113: 1112: 1111: 1106: 1067:Cassels, J.W.S. 1048: 1038:Springer-Verlag 1000: 990:Springer-Verlag 916:Whaples, George 877:Whaples, George 867: 862: 861: 853: 849: 841: 837: 829: 825: 817: 813: 805: 801: 793: 789: 781: 777: 772: 749: 732: 675: 671: 659: 654: 639: 635: 630: 624: 620: 619: 615: 610: 604: 599: 586: 582: 580: 577: 576: 555: 546: 517: 511: 495:quadratic forms 483: 477: 472: 456:Main Conjecture 440:Arakelov theory 403:of the field. 367: 362: 361: 353: 347: 341: 338: 337: 327:product formula 319:Dedekind domain 299: 241:and has finite 220:field extension 196: 188:Main articles: 186: 152: 148: 140: 137: 136: 131:, the field of 106: 101: 100: 98: 95: 94: 87:algebraic curve 58: 56: 53: 52: 12: 11: 5: 1146: 1136: 1135: 1130: 1125: 1110: 1109: 1104: 1086: 1059: 1046: 1020: 998: 978: 963: 960:Academic Press 948:J.W.S. Cassels 945: 926:(4): 245–247, 908: 889:(7): 469–492, 868: 866: 863: 860: 859: 847: 845:, p. 391. 835: 833:, p. 197. 823: 821:, p. 140. 811: 799: 787: 774: 773: 771: 768: 745: 733:stand for the 728: 695: 694: 683: 674: 670: 667: 662: 657: 653: 649: 642: 638: 633: 627: 623: 618: 613: 607: 602: 598: 594: 589: 585: 551: 542: 521:abelianization 513:Main article: 510: 507: 505:of the field. 479:Main article: 476: 473: 471: 468: 452:Iwasawa theory 393: 392: 381: 378: 375: 370: 365: 360: 356: 350: 346: 298: 295: 259: 258: 208: 207: 185: 182: 170: 169: 155: 151: 147: 144: 120: 117: 114: 109: 104: 80:function field 73: 61: 9: 6: 4: 3: 2: 1145: 1134: 1131: 1129: 1126: 1124: 1121: 1120: 1118: 1107: 1101: 1097: 1096: 1091: 1087: 1084: 1080: 1076: 1072: 1068: 1064: 1060: 1057: 1053: 1049: 1047:3-540-90424-7 1043: 1039: 1035: 1031: 1030: 1025: 1021: 1017: 1013: 1009: 1005: 1001: 995: 991: 987: 983: 979: 976: 975:0-521-31525-5 972: 968: 964: 961: 957: 953: 949: 946: 943: 939: 934: 929: 925: 921: 917: 913: 909: 906: 902: 897: 892: 888: 884: 883: 878: 874: 870: 869: 856: 855:Neukirch 1999 851: 844: 843:Neukirch 1999 839: 832: 827: 820: 815: 808: 803: 796: 791: 784: 783:Neukirch 1999 779: 775: 767: 765: 761: 757: 753: 748: 744: 740: 736: 731: 727: 723: 719: 715: 710: 708: 704: 700: 681: 672: 660: 655: 651: 640: 636: 631: 625: 621: 616: 611: 605: 600: 596: 592: 587: 583: 575: 574: 573: 571: 567: 563: 559: 554: 550: 545: 541: 536: 534: 530: 526: 522: 516: 506: 504: 500: 496: 492: 491:number theory 488: 482: 467: 465: 461: 457: 453: 449: 445: 444:Gerd Faltings 441: 436: 434: 430: 426: 421: 417: 414:goes back to 413: 409: 404: 402: 398: 379: 376: 373: 368: 358: 348: 344: 336: 335: 334: 332: 328: 324: 320: 316: 312: 308: 304: 294: 292: 288: 284: 280: 276: 272: 268: 264: 256: 255: 254: 252: 248: 244: 240: 236: 232: 229: 225: 221: 217: 213: 205: 204: 203: 201: 195: 191: 181: 179: 176:was given by 175: 153: 149: 145: 142: 134: 115: 107: 92: 88: 85: 81: 77: 74: 50: 46: 43: 42: 41: 39: 35: 31: 27: 23: 19: 1095:Local Fields 1094: 1074: 1071:Fröhlich, A. 1029:Local Fields 1027: 985: 955: 923: 919: 886: 880: 850: 838: 826: 814: 802: 790: 778: 763: 759: 755: 751: 746: 742: 738: 729: 725: 717: 713: 711: 706: 702: 698: 696: 569: 565: 562:local fields 552: 548: 543: 539: 537: 528: 525:Galois group 518: 498: 484: 437: 432: 405: 396: 394: 330: 326: 311:local fields 300: 286: 282: 278: 270: 266: 260: 250: 247:vector space 238: 234: 230: 211: 209: 200:global field 199: 197: 171: 91:finite field 75: 30:local fields 22:global field 21: 15: 952:A. Frohlich 912:Artin, Emil 873:Artin, Emil 741:. The maps 697:called the 427:settled by 303:completions 84:irreducible 18:mathematics 1117:Categories 1083:0153.07403 1056:0423.12016 1016:0956.11021 865:References 831:Serre 1979 819:Serre 1967 503:completion 429:AndrĂ© Weil 401:valuations 289:to be the 178:Emil Artin 34:valuations 770:Citations 669:→ 661:× 606:× 584:θ 345:∏ 243:dimension 216:algebraic 168:elements. 1073:(eds.), 1026:(1979), 984:(1999). 977:. P.56. 969:, 1986, 470:Theorems 454:and the 233:. Thus 1008:1697859 954:(eds), 942:0015382 905:0013145 705:or the 462:in the 222:of the 89:over a 1102:  1081:  1054:  1044:  1014:  1006:  996:  973:  940:  903:  743:θ 701:, the 568:. The 395:where 82:of an 78:: The 38:fields 26:fields 720:be a 556:be a 323:ideal 317:of a 309:(see 249:over 224:field 1100:ISBN 1042:ISBN 994:ISBN 971:ISBN 712:Let 538:Let 485:The 418:and 305:are 192:and 47:: A 20:, a 1079:Zbl 1052:Zbl 1012:Zbl 928:doi 891:doi 754:of 737:of 560:of 277:of 226:of 51:of 16:In 1119:: 1069:; 1050:, 1040:, 1010:. 1004:MR 1002:. 992:. 958:, 938:MR 936:, 924:52 922:, 914:; 901:MR 899:, 887:51 885:, 875:; 709:. 677:ab 333:: 253:. 218:) 198:A 40:: 1018:. 930:: 893:: 809:. 797:. 756:K 752:v 747:v 739:L 730:L 726:C 718:K 716:⁄ 714:L 682:, 673:G 666:) 656:v 652:L 648:( 641:v 637:K 632:/ 626:v 622:L 617:N 612:/ 601:v 597:K 593:: 588:v 566:G 553:v 549:K 547:⁄ 544:v 540:L 529:K 397:v 380:, 377:1 374:= 369:v 364:| 359:x 355:| 349:v 331:x 287:V 283:V 279:U 271:U 267:V 251:Q 239:Q 235:F 231:Q 212:F 154:n 150:p 146:= 143:q 119:) 116:T 113:( 108:q 103:F 60:Q

Index

mathematics
fields
local fields
valuations
fields
Algebraic number field
finite extension
function field
irreducible
algebraic curve
finite field
rational functions
valuation theory
Emil Artin
Algebraic number field
Function field of an algebraic variety
algebraic
field extension
field
rational numbers
dimension
vector space
algebraic variety
affine coordinate ring
field of fractions
completions
locally compact fields
local fields
field of fractions
Dedekind domain

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